In 1939, Lucie Bernard, the daughter of a wine grower, married Raymond Samuel (born July 31, 1914), a Jew, whom she met in Strasbourg. Raymond Samuel would later come to be known as Raymond Aubrac, having had to change his surname due to open anti-Semitism and persecution of Jews in France at the time.

After the fall of France, Lucie joined the Libération-sud resistance group in Lyon after its formation by her husband. Later, she followed him to the Charles Delestraint's group. In 1941 they joined forces with Emmanuel d'Astier to run the underground newspaper, Libération.

On June 21, 1943, the Gestapo captured Raymond alongside high-ranking Resistance member Jean Moulin (under the alias "Max") and many others. They were taken to Montluc prison, located near Lyon. The Nazis sought Jean Moulin in particular as he was General Charles de Gaulle's top representative in the French Resistance.

Lucie was able to talk face to face with Klaus Barbie, Lyon's Gestapo chief. Her alias was "Ghislaine de Barbentane", a name of high-standing, noble origin. Because of her pregnancy and a specific provision of French law called "marriage in extremis," under which a person condemned to death can marry civilly, Lucie managed to convince Barbie that a person in her situation could not be a mother without being married (known as a "fille-mère"). He unwisely allowed Raymond to be released for the wedding, which gave Lucie and the Resistance a fortunate opportunity.

On the day of their marriage, October 21, 1943, Lucie and her comrades attacked the German truck that was transporting the prisoners back to German command, and released Raymond along with the thirteen other members of the Resistance being held. Six Germans, including the truck driver and five guards, were killed during the attack and escape.

Having had their true identities revealed, Lucie, Raymond and their child left for London in February 1944. As it was the last alias they had used in France, Aubrac remained as their name in the United Kingdom. Their daughter Catherine, born on February 12, became de Gaulle's goddaughter.

After the war, Lucie Aubrac served on the consultative committees of the French Republic Provisional Government (GPRF). Her teaching degree was also restored, and she eventually returned to teaching. She was also active in the campaign for human rights.

In 1984 Lucie Aubrac published her memoirs under the title Ils partiront dans l'ivresse (best translated as "They will leave with elation"). The French title refers to the radio code phrase the Aubracs listened for to know it was safe for them to leave for London. The book was translated into English as Outwitting the Gestapo). The film Lucie Aubrac is loosely based on the events surrounding her husband's escape.

Lucie Aubrac died in Issy-les-Moulineaux, near Paris, on March 14, 2007.